Ofdma System, The Frequency Synchronization Technology Research, And Adaptive Resource Allocation

Much research has been devoted to Orthogonal Frequency Division Multiplexing (OFDM) in broadband wireless communication for its high spectral efficiency and ability in mitigating the effects of frequency selective or multipath channel propagation. Built upon OFDM, Orthogonal Frequency Division Multiple Access (OFDMA) is a new wireless access technique. It effectively combines the multiple access method with the modulation process, and has emerged as one of key technologies in future wireless mobile communication system. In this thesis, we present the basic principle of OFDMA system. For the uplink OFDMA system, the interleaved subcarrier allocation strategy results in the received signal a periodic structure. We propose an ESPRIT based algorithm to accurately estimate the multi-user frequency offset via subspace rotational invariance technique. For the OFDMA resource allocation problem, a QoS guaranteed adaptive subcarrier and power allocation algorithm is proposed. We allocate the subcarrier and power jointly in real time users' allocation process, to fulfill the transmission rate and object bit error rate requirements. Subcarrier and power allocation is performed separately for non-real time users with the proportional rate constraints. By using the linearized method, computational complexity is reduced greatly...